Nitrogen is an essential element for plant growth and yield. Improving Nitrogen Use Efficiency (NUE) of crops could potentially reduce the application of chemical fertilizer and alleviate environmental damage. To identify new NUE genes is therefore an important task in molecular breeding. Macroautophagy (autophagy) is an intracellular process in which damaged or obsolete cytoplasmic components are encapsulated in double membraned vesicles termed autophagosomes, then delivered to the vacuole for degradation and nutrient recycling. One of the core components of autophagosome formation, ATG8, has been shown to directly mediate autophagosome expansion, and the transcript of which is highly inducible upon starvation. Therefore, we postulated that certain homologs of Saccharomyces cerevisiae ATG8 (ScATG8) from crop species could have potential for NUE crop breeding. A soybean (Glycine max, cv. Zhonghuang-13) ATG8, GmATG8c, was selected from the 11 family members based on transcript analysis upon nitrogen deprivation. GmATG8c could partially complement the yeast atg8 mutant. Constitutive expression of GmATG8c in soybean callus cells not only enhanced nitrogen starvation tolerance of the cells but accelerated the growth of the calli. Transgenic Arabidopsis over-expressing GmATG8c performed better under extended nitrogen and carbon starvation conditions. Meanwhile, under optimum growth conditions, the transgenic plants grew faster, bolted earlier, produced larger primary and axillary inflorescences, eventually produced more seeds than the wild-type. In average, the yield was improved by 12.9%. We conclude that GmATG8c may serve as an excellent candidate for breeding crops with enhanced NUE and better yield.

A protein phosphatase negatively regulates Arabidopsis leaf senescence through dephosphorylating a senescence-promoting receptor-like kinase.

Background: Late embryogenesis abundant (LEA) proteins are a group of highly hydrophilic glycine-rich proteins, which accumulate in the late stage of seed maturation and are associated with many abiotic stresses. However, few peanut LEA genes had been reported, and the research on the number, location, structure, molecular phylogeny and expression of AhLEAs was very limited. Results: In this study, 126 LEA genes were identified in the peanut genome through genome-wide analysis and were further divided into eight groups. Sequence analysis showed that most of the AhLEAs (85.7%) had no or only one intron. LEA genes were randomly distributed on 20 chromosomes. Compared with tandem duplication, segmental duplication played a more critical role in AhLEAs amplication, and 93 segmental duplication AhLEAs and 5 pairs of tandem duplication genes were identified. Synteny analysis showed that some AhLEAs genes come from a common ancestor, and genome rearrangement and translocation occurred among these genomes. Almost all promoters of LEAs contain ABRE, MYB recognition sites, MYC recognition sites, and ERE cis-acting elements, suggesting that the LEA genes were involved in stress response. Gene transcription analyses revealed that most of the LEAs were expressed in the late stages of peanut embryonic development. LEA3 (AH16G06810.1, AH06G03960.1), and Dehydrin (AH07G18700.1, AH17G19710.1) were highly expressed in roots, stems, leaves and flowers. Moreover, 100 AhLEAs were involved in response to drought, low-temperature, or Al stresses. Some LEAs that were regulated by different abiotic stresses were also regulated by hormones including ABA, brassinolide, ethylene and salicylic acid. Interestingly, AhLEAs that were up-regulated by ethylene and salicylic acid showed obvious subfamily preferences. Furthermore, three AhLEA genes, AhLEA1, AhLEA3-1, and AhLEA3-3, which were up-regulated by drought, low-temperature, or Al stresses was proved to enhance cold and Al tolerance in yeast, and AhLEA3-1 enhanced the drought tolerance in yeast. Conclusions: AhLEAs are involved in abiotic stress response, and segmental duplication plays an important role in the evolution and amplification of AhLEAs. The genome-wide identification, classification, evolutionary and transcription analyses of the AhLEA gene family provide a foundation for further exploring the LEA genes’ function in response to abiotic stress in peanuts.

Background: Tuberous root formation and development is a complex process in sweet potato, which is regulated by multiple genes and environmental factors. However, the regulatory mechanism of tuberous root development is unclear.Results: In this study, the transcriptome of fibrous roots (R0) and tuberous roots in three developmental stages (Rl, R2, R3) were analyzed in two sweet potato varieties, GJS-8 and XGH. A total of 22,914 and 24,446 differentially expressed genes (DEGs) were identified in GJS-8 and XGH respectively, 15,920 differential genes were shared by GJS-8 and XGH. KEGG pathway enrichment analysis showed that the DEGs shared by GJS-8 and XGH were mainly involved in “plant hormone signal transduction” “starch and sucrose metabolism” and “MAPK signal transduction”. Trihelix transcription factor (Tai6.25300) was found to be closely related to tuberous root enlargement by the comprehensive analysis of these DEGs and weighted gene co-expression network analysis (WGCNA).Conclusion: A hypothetical model of genetic regulatory network for tuberous root development of sweet potato is proposed, which emphasizes that some specific signal transduction pathways like “plant hormone signal transduction” “Ca²⁺signal” “MAPK signal transduction” and metabolic processes including “starch and sucrose metabolism” and “cell cycle and cell wall metabolism” are related to tuberous root development in sweet potato. These results provide new insights into the molecular mechanism of tuberous root development in sweet potato.

Post-transcriptional control of the expression of the 1-aminocyclopropane-1-carboxylate synthase (ACS) gene family is important for maintaining appropriate levels of ethylene production. However, the molecular mechanism underlying the post-transcriptional regulation of type 3 ACS proteins remains unclear. Multiple sequence alignment revealed that the N-terminus of type 3 ACSs was longer than that of other ACSs. Fusing the N-terminal 54 residues of ACS7, the sole type 3 ACS in Arabidopsis, to the β-glucuronidase (GUS) reporter significantly decreased the stability of N^7(1–54)–GUS fusion protein. Among these 54 residues, residues 1–14 conferred this negative effect on the GUS fusion gene. Consistently, a truncated form of ACS7 lacking residues 1–14 was more stable than full-length ACS7 when transgenically expressed in Arabidopsis and led to a more severe ethylene response phenotype in the light-grown transgenic seedlings. Interestingly, the ACS7 N-terminus had no effect on the stability of N⁷–GUS and ACS7 proteins at the etiolated seedling stage. Both exogenous 1-aminocyclopropane-1-carboxylic acid (ACC) treatment and salt stress could rescue the levels of accumulation of N⁷–GUS fusion protein in light-grown seedlings. These results suggest that the non-catalytic N-terminus of ACS7 is involved in its own post-translational regulation. The proteasome inhibitor MG132 suppressed degradation of full-length ACS7 in vivo, but had little effect on the N-terminal truncated form of ACS7, indicating that the N-terminus mediates the regulation of ACS7 stability through the ubiquitin–26S proteasome pathway.