Cold tolerance adaption is a crucial determinant for the establishment and expansion of invasive alien plants into new cold environments; however, its evolutionary mechanism is poorly understood. Crofton weed (Ageratina adenophora), a highly invasive alien plant, is continuously spreading across subtropical areas in China, north-eastward from the first colonized south-western tropical regions, through cold tolerance evolution. Close relations between the cold tolerance levels of 34 populations, represented by 147 accessions, and the latitude, extreme lowest temperature, coldest month average temperature, and invasion period have provided direct insight into its cold tolerance divergence. A comparative study of the CBF pathway, associated with the cold tolerance enhancement of cold-susceptible CBF1-transgenic plant, among four geographically distinct crofton weed populations revealed that the CBF pathway plays a key role in the observed cold tolerance divergence. Four epialleles of the cold response regulator ICE1 ranged from 66 to 50 methylated cytosines, representing a 4.4% to 3.3% methylation rate and significantly corresponding to the lowest to highest cold tolerance levels among these different populations. The significant negative relation between the transcription levels of the primary CBF pathway members, except for CBF2, and the methylation levels among the four populations firstly demonstrates that the demethylation-upregulated transcription level of CBF pathway is responsible for this evolution. These facts, combined with the cold tolerance variation and methylation found among three native and two other introduced populations, indicate that the ICE1-demethylated upregulation of cold tolerance may be the underlying evolutionary mechanism allowing crofton weed to expand northward in China.

Wheat plants were subjected to combined waterlogging and shading stress (WS) at 0–7, 8–15, 16–23 and 24–31 days after anthesis (DAA), respectively. Compared to the non‐stressed plants, WS significantly decreased the final grain yield. Grain number was dramatically lowered by WS imposed at 0–7 DAA but hardly affected by other WS treatments; while the thousand‐kernel‐weight was unaffected by WS imposed at 0–7 DAA and lowered by other WS treatments. Photosynthate accumulation in the stem was decreased by WS imposed at 0–7 and 8–15 DAA, but was unaffected by WS imposed at later stages. Grain‐filling rate was decreased, although the apparent remobilization of carbohydrate reserves from stem to grain was stimulated under WS. The carbohydrate reserves stored in the lower stem internodes were activated earlier and remobilized much more than those in the upper internodes; however, the proportion of the apparent remobilized reserves among the different stem internodes was consistent for all treatments. WS decreased contents of fructans, fructose and sucrose in the stem, which coincided with increased activity of fructan exohydrolase and decreased activities of sucrose‐1‐fructosyltransferase and fructan‐1‐fructosyltransferse. The results indicate that post‐anthesis WS stimulated carbohydrate reserves remobilization by modifying the activities of the fructans‐catalysing enzymes in the stem.

Plants secrete defense molecules into the extracellular space (the apoplast) to combat attacking microbes. However, the mechanisms by which successful pathogens subvert plant apoplastic immunity remain poorly understood. In this study, we show that PsAvh240, a membrane-localized effector of the soybean pathogen Phytophthora sojae, promotes P. sojae infection in soybean hairy roots. We found that PsAvh240 interacts with the soybean-resistant aspartic protease GmAP1 in planta and suppresses the secretion of GmAP1 into the apoplast. By solving its crystal structure we revealed that PsAvh240 contain six a helices and two WY motifs. The first two a helices of PsAvh240 are responsible for its plasma membrane-localization and are required for PsAvh240's interaction with GmAP1. The second WY motifs of two PsAvh240 molecules form a handshake arrangement resulting in a handshake-like dimer. This dimerization is required for the effector's repression of GmAP1 secretion. Taken together, these data reveal that PsAvh240 localizes at the plasma membrane to interfere with GmAP1 secretion, which represents an effective mechanism by which effector proteins suppress plant apoplastic immunity.

Meloidogyne incognita is the most economically important plant‐parasitic nematode. Meloidogyne incognita manipulates plant cell development and metabolism by injecting effectors from the oesophageal glands into the plant host. Chorismate mutase (CM) is one such effector that may contribute to successful parasitism by M. incognita. This investigation identified and functionally characterized a novel CM effector, Mi‐CM‐3, which is more similar to CMs from bacteria than from other phytoparasitic nematodes. Spatial and temporal expression assays showed Mi‐cm‐3 mRNA accumulates specifically in the subventral oesophageal glands and transcription is up‐regulated during the early parasitic stages of the nematode. In planta gene silencing of Mi‐cm‐3 attenuated nematode parasitism. In addition, Mi‐cm‐3 could fully restore the full virulence phenotype of the pathogenic bacterium Xanthomonas oryzae pv. oryzae by complementation when it was introduced into a mutant strain carrying a deletion in the CM gene. Transient expression of Mi‐CM‐3 caused a reduction in levels of salicylic acid (SA) and mRNA of gene PR1 in Nicotiana benthamiana in response to oomycete pathogen Phytophthora capsici infection, while confocal observations showed that Mi‐CM‐3 was localized within the cytoplasm and the nucleus, but not the plastids, of transfected N. benthamiana leaf cells. Constitutive expression of Mi‐CM‐3 in N. benthamiana plants inhibited root growth and increased susceptibility to M. incognita infection. These results provide direct experimental evidence to show that Mi‐CM‐3 may play an important role in suppressing plant immunity by regulating the SA pathway during the early parasitic stage of M. incognita so as to promote nematode parasitism.

Understanding how fertilization practices affect Al fractions is important for the alleviation of soil acidification and the sequestration of soil organic C (SOC). Two selective extraction methods, high‐resolution 27Al nuclear magnetic resonance (NMR) spectroscopy and Fourier‐transform infrared spectroscopy (FTIR), were used to assess the transformation of Al fractions in Ferralic Cambisol soils under long‐term (22‐yr) treatment with chemical and/or organic fertilizers. The results showed that Al fractions were significantly (P < 0.05) altered by long‐term fertilization. Compared with chemical fertilization (N and N–P–K), organic fertilization (manure alone and N–P–K with manure) significantly (P < 0.05) increased amorphous Al and decreased exchangeable Al, while the addition of lime (N with lime and N–P–K with lime) significantly (P < 0.05) increased weakly organically bound Al and decreased exchangeable Al. Amorphous Al was significantly positively correlated with soil C (P < 0.01), indicating that amorphous Al could enhance soil C sequestration. In contrast, exchangeable Al was significantly negatively correlated with soil pH (P < 0.01), indicating that reducing the concentration of exchangeable Al could alleviate soil acidification. The 27Al NMR and FTIR spectroscopy results of soil colloids further confirmed the presence of amorphous Al as allophane and imogolite in soil colloids under no‐fertilization and organic‐fertilization treatments but not under chemical fertilization, suggesting that the enhancement of soil nanominerals by organic fertilization may be another new mechanism for alleviating soil acidification. Our results provide novel insight into how Al fractions and their coordinate states under long‐term fertilization enhance soil C sequestration while alleviating soil acidification.

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Accumulations of high molecular weight glutenin subunits (HMW‐GS) and glutenin macropolymer (GMP) in wheat grains are important indicators of grain quality. Two wheat cultivars, Yangmai 158 (shading tolerant) and Yangmai 11 (shading intolerant) which contains the same subunit pairs of 7 + 8 and 2 + 12, were used to evaluate the impacts of shading on HMW‐GS accumulation and GMP concentration in the grain. Three shading levels were implemented from jointing to maturity, i.e. S1, S2 and S3, in which the plants received 8 %, 15 % and 23 % less radiation of the control (S0), respectively. The initial formation of HMW‐GS was pre‐dated by shading. The rapid HMW‐GS accumulation duration was shortened, and the accumulation rate during late grain filling period was lowered in the two relatively severe shaded treatments (S2 & S3). Thus, the total HMW‐GS accumulation in single grain at maturity was lower in S2 and S3 than in the control (S0). However, concentrations of HMW‐GS and GMP at maturity increased because of the reduced single grain weight in S2 and S3, as compared to S0. In contrast, the low density shading (S1) prolonged the rapid accumulation duration of HMW‐GS, hence increased the accumulation and concentration of HMW‐GS in the grains. Consequently, S1 reduced falling number and SDS‐sedimentation volume, while shortened dough development time (DDT) and dough stability time (DST). In contrast, S2 and S3 increased falling number, wet‐gluten concentration and SDS‐sedimentation volume, and lengthened the DDT and DST. In addition, the fluctuations in accumulations of HMW‐GS and GMP and most quality traits because of shading in Yangmai 158 were less than Yangmai 11. The interrelations between HMW‐GS accumulation, GMP concentration and quality of grain and dough were further discussed.

Ascorbic acid (AsA), also known as ascorbate or vitamin C, is a natural organic compound in green plants that has antioxidant properties, and is an essential nutrient for humans. The tea plant, Camellia sinensis (L.) O. Kuntze, is an important global economic crop. Here, the expression profiles of genes related to AsA biosynthesis and recycling were analyzed in tea plants in response to temperature stress. Eighteen genes involved in AsA biosynthesis and recycling pathways were identified based on the transcriptome database. The expression levels of CsPGI1 in two varieties of tea plants ('Yingshuang' and 'Huangjinya') increased, peaked at 4 h, and then decreased in response to cold stress. In 'Yingshuang', the genes involved in AsA biosynthesis pathway rapidly responded to heat stress and substantially increased their expression levels at 1 h. The expression levels of CsMDHAR, CsDHAR1, and CsDHAR2 increased sharply at 1 h in response to heat stress in 'Yingshuang'. In contrast, the expression levels of CsMDHAR, CsDHAR1, and CsDHAR2 in 'Huangjinya' gradually increased during heat treatment from 1 to 24 h. The expression trends of two DHAR isoforms differed in 'Huangjinya' during cold stress. The expression patterns of AsA-related genes differed in the different tea plant varieties and depended on temperature. The genes involved in AsA biosynthesis and recycling pathways were induced by heat and cold stress. Our study provides useful data with which to improve the resistance of tea plants to cold and heat stress.