Chloroplasts are essential for plant photosynthesis and growth. Many genes have been identified that regulate plant chloroplast development. However, it is not known at a molecular level how these genes regulate chloroplast biogenesis. In this study, we isolated a mutant ygl2 (yellow-green leaf2) that exhibited a pigment-defective phenotype. YGL2 encodes a geranylgeranyl reductase, and in mutant ygl2, there was a single base change (T1361G) located in the third exon of YGL2 that resulted in a missense mutation (L454R) in the encoded product. Transmission electron microscopy revealed that chloroplast development was impaired in the ygl2 mutant. The expression levels of plastid-encoded genes were significantly altered in the ygl2 mutant. Furthermore, in a yeast two-hybrid assay, we found that YGL2 interacted with the RNA editing factor MORF8.

Synthetic hexaploid wheat (SHW), possesses numerous genes for drought that can help breeding for drought-tolerant wheat varieties.  We evaluated 10 root traits at seedling stage in 111 F₉ recombinant inbred lines derived from a F₂ population of a SHW line (SHW-L1) and a common wheat line, under normal (NC) and polyethylene glycol-simulated drought stress conditions (DC).  We mapped quantitative trait loci (QTLs) for root traits using an enriched high-density genetic map containing 120 370 single nucleotide polymorphisms (SNPs), 733 diversity arrays technology markers (DArT) and 119 simple sequence repeats (SSRs).  With four replicates per treatment, we identified 19 QTLs for root traits under NC and DC, and 12 of them could be consistently detected with three or four replicates.  Two novel QTLs for root fresh weight and root diameter under NC explained 9 and 15.7% of the phenotypic variation respectively, and six novel QTLs for root fresh weight, the ratio of root water loss, total root surface area, number of root tips, and number of root forks under DC explained 8.5–14% of the phenotypic variation.  Here seven of eight novel QTLs could be consistently detected with more than three replicates.  Results provide essential information for fine-mapping QTLs related to drought tolerance that will facilitate breeding drought-tolerant wheat cultivars.

    Alcohol dehydrogenase (ADH) catalyzes the interconversion of aldehydes and their corresponding alcohols, and is a key enzyme in volatile ester biosynthesis. However, little is known regarding ADH and ADH encoding genes (ADHs) in pear. We identified 8 ADHs in the pear’s genome (PbrADHs) by multiple sequences alignment. The PbrADHs were highly homologous in their coding regions, while were diversiform in structure. 9 introns were predicted in PbrADH₃–PbrADH₈, while 8 introns, generated through exon fusion and intron loss, were predicted in PbrADH₁ and PbrADH₂. To study the genetic regulation underlying aroma biogenesis in pear fruit, we determined the PbrADH transcripts, ADH activities and volatile contents of fruits during ripening stage for Nanguoli and Dangshansuli, two cultivars having different aroma characteristics. ADH activity was strongly associated with the transcription of ADH6 in the two cultivars during fruit ripening stage. The higher ester content paralleling to a higher ADH activity was detected in Nanguoli than in Dangshansuli, so it is induced that the lower ester content in Dangshansuli fruit may be the result of weak ADH activity. The present study revealed that total ADH activity and volatile ester production correlated with increased PbrADH₆ transcript levels. PbrADH6 may contribute to ADH activity catalyzing aldehyde reduction and ester formation in pear fruit.

Increasing grain yield (GY) and water use efficiency (WUE) of winter wheat in the Huaibei Plain (HP) is essential.  However, the effects of micro-sprinkler irrigation and topsoil compaction after wheat seeds sowing on the GY and WUE are unclear.  Therefore, a two-year field experiment was conducted during the 2021–2023 winter wheat growing seasons with a total six treatments: rain-fed (RF), conventional irrigation (CI) and micro-sprinkler irrigation (MI), as well as topsoil compaction after seeds sowing under three irrigation methods (RFC, CIC, and MIC).  The two years’ results indicated that MI significantly increased GY compared to CI and RF, which averagely increased by 17.9 and 42.1%, respectively.  The increase in GY of MI was due to its significant increase in the number of spikes, kernels per spike, and grain weight.  Chlorophyll concentration in flag leaves of MI after anthesis stage was maintained higher levels than CI and RF, RF was the lowest.  This was due to the dramatically enhanced catalase and peroxidase activity and lower malondialdehyde content under MI.  Compared with RF and CI, MI significantly promoted dry matter remobilization and production after anthesis as well as its contribution to GY.  In addition, MI significantly boosted root growth, and root activity during grain filling stage was remarkably enhanced than CI and RF.  In 2021–2022, there was no significant difference in WUE between MI and RF, but the WUE of RF was significantly lower than MI in 2022–2023.  However, WUE in MI was significantly improved compared to CI, that averagely increased by 15.1 and 17.6% for the two years.  Topsoil compaction significantly increased GY and WUE under rain-fed conditions due to improved spike numbers and dry matter production.  Overall, topsoil compaction is advisable for enhancing GY and WUE in rain-fed conditions, whereas micro-sprinkler irrigation can be adopted to achieve high GY and WUE simultaneously in the HP.