Rice Science最新文献

Aromatic rice is considered an important commodity in the global market because of its strong aroma and eating and cooking quality. Asian countries, such as India and Pakistan, are the leading traders of Basmati rice, whereas Thailand is the major supplier of Jasmine rice in the international market. The strong aroma of rice is associated with more than 300 volatile compounds, among which 2-acetyl-1-pyrroline (2-AP) is the principal component. 2-AP is a phenotypic expression of spontaneous mutations in the recessive gene OsBadh2 or Badh2. The present review focuses on the origin, evolution and diversity of genetic resources of aromatic rice available worldwide. A brief discussion is presented on the genes responsible for quality traits along with details of their molecular genetics. This compilation and discussion will be useful for future breeding programs and the biofortification of quality traits of aromatic rice to ensure food security and nutritional need.

Assessing the impact of climate change (CC) on agricultural production systems is mainly done using crop models associated with climate model outputs. This review is one of the few, with the main objective of providing a recent compendium of CC impact studies on irrigation needs and rice yields for a better understanding and use of climate and crop models. We discuss the strengths and weaknesses of climate impact studies on agricultural production systems, with a particular focus on uncertainty and sensitivity analyses of crop models. Although the new generation global climate models (GCMs) are more robust than previous ones, there is still a need to consider the effect of climate uncertainty on estimates when using them. Current GCMs cannot directly simulate the agro-climatic variables of interest for future irrigation assessment, hence the use of intelligent climate tools. Therefore, sensitivity and uncertainty analyses must be applied to crop models, especially for their calibration under different conditions. The impacts of CC on irrigation needs and rice yields vary across regions, seasons, varieties and crop models. Finally, integrated assessments, the use of remote sensing data, climate smart tools, CO₂ enrichment experiments, consideration of changing crop management practices and multi-scale crop modeling, seem to be the approaches to be pursued for future climate impact assessments for agricultural systems.

Rice is sensitive to salinity stress at both the seedling and reproductive stages. The present study used 145 rice genotypes comprising of 100 landraces and 45 advanced breeding lines collected from different regions of India. These genotypes were evaluated in hydroponics under control [electrical conductivity (EC_e) ∼1.2 dS/m] and saline (EC_e ∼10.0 dS/m) environments along with susceptible (IR29) and tolerant (FL478) checks. The stress susceptibility index for eight morphophysiological traits was estimated. Analysis of variance showed significant differences among the genotypes for all the parameters studied in control, stress and relative stress conditions. We identified 3 landraces (Kuttimanja, Tulasimog and IET-13713I) as tolerant and 14 lines as moderately tolerant to salt stress. Strong correlations in the morphological (root and shoot lengths) and physiological traits (shoot Na⁺, Ca²⁺ and Mg²⁺ contents, and Na⁺/K⁺ ratio) were observed under all the conditions. The hierarchical cluster analysis grouped the genotypes into five clusters, among which cluster II comprised salt-tolerant lines. Haplotyping of Saltol region using 11 simple sequence repeat markers on 17 saline tolerant and moderately tolerant lines was conducted. Markers AP3206F, RM10793 and RM3412b, located close to SKC1 gene (11.23‒12.55 Mb), displayed diverse allelic variations and they were not related to the FL478 type. In this region, tolerant lines like Kuttimanja, IET-13713I and Tulasimog have new alleles. As a result, these lines may be suitable candidates for novel genomic regions governing rice salinity tolerance. Salt-tolerance ability of Kuttimanja, Tulasimog and IET-13713I was validated in two years in three salinity stress environments. These promising lines can be used in breeding programs to broaden the genetic base of salinity tolerance in rice, and it may help to dissect key genomic regions responsible for salinity tolerance.

Crop yield and quality are often limited by the amount of phosphate fertilizer added to infertile soils, a key limiting factor for sustainable development in modern agriculture. The polyphosphate kinase (ppk) gene -expressing transgenic rice with a single-copy line (ETRS) is constructed to improve phosphate fertilizer utilization efficiency for phosphorus resource conservation. To investigate the potential mechanisms of the increased biomass in ETRS in low phosphate culture, ETRS was cultivated in a low inorganic phosphate (Pi) culture medium (15 μmol/L Pi, LP) and a normal Pi culture medium (300 μmol/L Pi, CP), respectively. After 89 d of cultivation in different concentrations of phosphate culture media, the total phosphorus, polyphosphate (polyP), biomass, photosynthetic rate, nonstructural carbohydrate (NSC) contents, related enzyme activities, and related gene expression levels were analyzed. The results showed that ETRS had a high polyP amount to promote the photosynthetic rate in LP, and its biomass was almost the same as the wild type (WT) in CP. The NSC content of ETRS in LP was higher than that of WT in LP, but slightly lower than that of WT in CP. PolyP notably promoted the sucrose phosphate synthase activities of ETRS and significantly down-regulated the expression levels of sucrose transporter genes (OsSUT3 and OsSUT4), resulting in inhibiting the transport of sucrose from shoot to root in ETRS. It was concluded that polyP can stimulate the synthesis of NSCs in LP, which improved the growth of ETRS and triggered the biological activities of ETRS to save phosphate fertilizer. Our study provides a new way to improve the utilization rate of phosphate fertilizer in rice production.

Nitrate (NO₃^–) and ammonium (NH₄⁺) are two main inorganic nitrogen (N) sources during crop growth. Here, we enhanced the expression of OsAMT1.1, which encodes a NH₄⁺ transporter, using the NO₃^–-inducible promoter of OsNAR2.1 and an ubiquitin promoter in transgenic rice plants. Under field condition of 120 kg /hm² N, agronomic N use efficiency, N recovery efficiency and N transport efficiency, and grain yield of the pOsNAR2.1:OsAMT1.1 transgenic lines were increased compared with those of the wild type (WT) and the pUbi:OsAMT1.1 transgenic plants. Under 2.0 mmol/L NO₃^– + 0.5 mmol/L NH₄⁺ and 0.5 mmol/L NO₃^– + 2.0 mmol/L NH₄⁺ conditions of hydroponic culture, compared with the WT, both biomass and total N content were increased in the pOsNAR2.1:OsAMT1.1 transgenic lines. However, biomass was significantly reduced in pUbi:OsAMT1.1 transgenic plants under 0.5 mmol/L NO₃^– + 2.0 mmol/L NH₄⁺ condition. The lines expressing pOsNAR2.1:OsAMT1.1 exhibited increased OsAMT1.1 expression and ¹⁵NH₄⁺ influx in roots under both 2.0 mmol/L NO₃^– + 0.5 mmol/L NH₄⁺ and 0.5 mmol/L NO₃^– + 2.0 mmol/L NH₄⁺ conditions. Our study showed that expression of OsAMT1.1 can be promoted when driven by the OsNAR2.1 promoter, especially under high-level nitrate condition, leading to enhancement of NH₄⁺ uptake, N use efficiency and grain yield.