Low-density lipoprotein receptor-related protein 2 (LRP2) is a multifunctional endocytic receptor expressed in epithelial cells.  In mammals, it acts as an endocytic receptor that mediates the cellular uptake of cholesterol-containing apolipoproteins to maintain lipid homeostasis.  However, little is known about the role of LRP2 in lipid homeostasis in insects.  In the present study, we investigated the function of LRP2 in the migratory locust Locusta migratoria (LmLRP2).  The mRNA of LmLRP2 is widely distributed in various tissues, including integument, wing pads, foregut, midgut, hindgut, Malpighian tubules and fat body, and the amounts of LmLRP2 transcripts decreased gradually in the early stages and then increased in the late stages before ecdysis during the nymphal developmental stage.  Fluorescence immunohistochemistry revealed that the LmLRP2 protein is mainly located in cellular membranes of the midgut and hindgut.  Using RNAi to silence LmLRP2 caused molting defects in nymphs (more than 60%), and the neutral lipid was found to accumulate in the midgut and surface of the integument, but not in the fat body, of dsLmLRP2-treated nymphs.  The results of a lipidomics analysis showed that the main components of lipids (diglyceride and triglyceride) were significantly increased in the midgut, but decreased in the fat body and hemolymph.  Furthermore, the content of total triglyceride was significantly increased in the midgut, but markedly decreased in the fat body and hemolymph in dsLmLRP2-injected nymphs.  Our results indicate that LmLRP2 is located in the cellular membranes of midgut cells, and is required for lipid export from the midgut to the hemolymph and fat body in locusts.

Wings are an important flight organ of insects.  Wing development is a complex process controlled by a series of genes.  The flightless wing pad transforms into a mature wing with the function of migratory flight during the nymph-to-adult metamorphosis.  However, the mechanism of wing morphogenesis in locusts is still unclear.  This study analyzed the microstructures of the locust wing pads at pre-eclosion and the wings after eclosion and performed the comparative transcriptome analysis.  RNA-seq identified 25,334 unigenes  and 3,430 differentially expressed genes (DEGs) (1,907 up-regulated and 1,523 down-regulated).  The DEGs mainly included cuticle development (LmACPs), chitin metabolism (LmIdgf4), lipid metabolism-related genes, cell adhesion (Integrin), zinc finger transcription factors (LmSalm, LmZF593 and LmZF521), and others.  Functional analysis based on RNA interference and hematoxylin and eosin (H&E) staining showed that the three genes encoded zinc finger transcription factors are essential for forming wing cuticle and maintaining morphology in Locusta migratoria.  Finally, the study found that the LmSalm regulates the expression of LmACPs in the wing pads at pre-eclosion, and LmZF593 and LmZF521 regulate the expression of LmIntegrin/LmIdgf4/LmHMT420 in the wings after eclosion.  This study revealed that the molecular regulatory axis controls wing morphology in nymphal and adult stages of locusts, offering a theoretical basis for the study of wing development mechanisms in hemimetabolous insects.

Rapeseed (Brassica napus L.) is one of the most important oilseed crops worldwide.  Development of rapeseed varieties with high-quality oil is a long-term breeding goal.  Reducing the contents of palmitic acid, the main saturated fatty acid in rapeseed oil, could greatly improve oil quality.  Here, we performed genome-wide association study (GWAS) and transcriptome-wide association study (TWAS) of seed palmitic acid content (SPAC) using 393 diverse B. napus accessions.  Four genes (BnaA08.DAP, BnaA08.PAA1, BnaA08. DUF106, and BnaC03.DAP) were identified by both GWAS and TWAS.  The transcripts per million (TPM) values of these candidate genes at 20 and 40 days after flowering (DAF) were significantly correlated with SPAC in this association panel.  Based on genetic variation in the candidate genes, we identified four low-SPAC haplotypes by combining candidate gene association analysis and haplotype analysis.  Brassica napus accessions carrying low-SPAC haplotypes had lower SPAC than those carrying high-SPAC haplotypes without affecting seed oil content, seed protein content, or seed yield.  Based on the functional single-nucleotide polymorphism (SNP) chrA08_9529850 (C/A) in the promoter of BnaA08.DUF106, we developed a molecular marker (Bn_A8_SPAC_Marker) that could be used to facilitate breeding for low SPAC in B. napus.  Our findings provide valuable information for studying the genetic control of SPAC in B. napus.  Moreover, the candidate genes, favorable haplotypes, and molecular marker identified in this study will be useful for breeding low-SPAC B. napus varieties.

Water-driven crop simulation models are commonly employed to evaluate crop yields and irrigation management strategies to improve agricultural water productivity.  Well-tested models can serve as powerful tools for guiding agricultural practices.  The objective of this study was to assess the capability of the AquaCrop model for simulation of cotton transpiration and water use under drip irrigation conditions comparing with field sap flow measurements.  A two-year field experiment (2020-2021) in cotton was conducted in Xinjiang China including two row spacing and two topping methods.  The model adequately estimated canopy cover with a normalized root mean square error (nRMSE) of less than 5% and a model efficiency (EF) close to 1.  The model estimation of transpiration obtained a good agreement with sap flow measurements (nRMSE=22.4%) across all years and treatments.  The model simulated water use efficiency (WUE, 4.42 g m^-2 mm^-1) of cotton were lower than those calculated from actual measurements with WUE of 4.79 g m^-2 mm^-1.  The estimated transpiration was slightly higher than that measured using sap flow meter due to an 11.5% of overestimation for crop coefficient in the model when cotton grew in short and dense canopy structure under drip irrigation and plastic film cover conditions.  Air temperature, vapor pressure difference and radiation had positive effects on cotton transpiration while humidity had negative effects.  The model could capture the trends of transpiration with climate factors, but the climatic effects were stronger than that of sap flow.  In conclusion, AquaCrop model is useful tool in optimizing cotton irrigation strategies.

The tiller number is a pivotal agronomic trait determining sugarcane (Saccharum spp. hybrids) yield. Strigolactones (SLs), as plant hormones, regulate plant architecture. DWARF27 (D27), a crucial enzyme in the SL biosynthetic pathway, catalyzes a reversible isomerization reaction. ScD27.2, the D27 homolog in sugarcane, harbors abiotic stress-responsive elements in its promoter, suggesting its significance in SL biosynthesis and stress tolerance. ScD27.2 may optimize sugarcane agronomic traits, particularly the tiller number and yield. Elucidating its mechanisms will facilitate the development of high-yielding, stress-tolerant sugarcane varieties. To study the role of D27 in sugarcane tillering, we silenced (via RNA interference (RNAi)) and overexpressed (OE) the key carotene isomerase gene ScD27.2 in sugarcane cultivar XTT22 plantlets. ScD27.2 expression decreased, and the tiller number increased in ScD27-RNAi-2 sugarcane compared with wild-type XTT22. ScD27.2 expression increased, and the tiller number decreased in ScD27-OE-1, ScD27-OE-5, and ScD27-OE-9 lines compared with wild-type XTT22. ScD27-OE-9 showed obvious lateral bud germination, while ScD27-RNAi-2 showed decreased drought tolerance. The tiller number and plant height of transgenic sugarcane plants differed significantly under normal light and water management conditions. Under long-term drought, the height of ScD27-RNAi-2 was significantly lower than that of wild-type XTT22 and ScD27-OE-9, exhibiting a dwarf, multi-tiller phenotype. Moreover, the SLs content in ScD27-RNAi-2 decreased significantly. We speculate that ScD27.2 regulates the tiller number of sugarcanes under drought stress, and the drought-related transcription factor ScMYB44 might be involved in the response of ScD27.2 to drought stress.