Effects of Peanut Rust Disease (Puccinia arachidis Speg.) on Agricultural Production: Current Control Strategies and Progress in Breeding for Resistance.

Peanuts play a pivotal role as an economic crop on a global scale, serving as a primary source of both edible oil and protein. Peanut rust (Puccinia arachidis Speg.) disease constitutes a significant global biotic stress, representing a substantial economic threat to the peanut industry by inducing noteworthy reductions in seed yields and compromising oil quality. This comprehensive review delves into the distinctive characteristics and detrimental symptoms associated with peanut rust, scrutinizing its epidemiology and the control strategies that are currently implemented. Notably, host resistance emerges as the most favored strategy due to its potential to surmount the limitations inherent in other approaches. The review further considers the recent advancements in peanut rust resistance breeding, integrating the use of molecular marker technology and the identification of rust resistance genes. Our findings indicate that the ongoing refinement of control strategies, especially through the development and application of immune or highly resistant peanut varieties, will have a profound impact on the global peanut industry.

OsABCG15 encodes a membrane protein that plays an important role in anther cuticle and pollen exine formation in rice.

KEY MESSAGE: An ABC transporter gene ( OsABCG15 ) was proven to be involved in pollen development in rice. The corresponding protein was localized on the plasma membrane using subcellular localization. Wax, cutin, and sporopollenin are important for normal development of the anther cuticle and pollen exine, respectively. Their lipid soluble precursors, which are produced in the tapetum, are then secreted and transferred to the anther and microspore surface for polymerization. However, little is known about the mechanisms underlying the transport of these precursors. Here, we identified and characterized a member of the G subfamily of ATP-binding cassette (ABC) transporters, OsABCG15, which is required for the secretion of these lipid-soluble precursors in rice. Using map-based cloning, we found a spontaneous A-to-C transition in the fourth exon of OsABCG15 that caused an amino acid substitution of Thr-to-Pro in the predicted ATP-binding domain of the protein sequence. This osabcg15 mutant failed to produce any viable pollen and was completely male sterile. Histological analysis indicated that osabcg15 exhibited an undeveloped anther cuticle, enlarged middle layer, abnormal Ubisch body development, tapetum degeneration with a falling apart style, and collapsed pollen grains without detectable exine. OsABCG15 was expressed preferentially in the tapetum, and the fused GFP-OsABCG15 protein was localized to the plasma membrane. Our results suggested that OsABCG15 played an essential role in the formation of the rice anther cuticle and pollen exine. This role may include the secretion of the lipid precursors from the tapetum to facilitate the transfer of precursors to the surface of the anther epidermis as well as to microspores.

Characterization and mapping of a male-sterility mutant, tapetum desquamation (t), in rice.

A spontaneously mutated male-sterile material was found among the offspring of the indica restorer line Jinhuiyihao. To understand the status and function of the related gene and clone the gene, a near-isogenic line (NIL) of the male sterility was bred, and characterization of the mutant and gene mapping were performed. The results indicated that there are obvious differences between the male-sterile NIL and the indica maintainer line II-32B. The anther size of the NIL is smaller than that of II-32B, and the anther color is white in the NIL but yellow in II-32B. No pollen from the matured anther in the NIL was observed to be stained using KI-I2 solution. In transverse sections of the sterile anther, at early microspore stage the cytoplasm of the tapetum concentrates but the tapetum itself does not degenerate after microspores are released from the tetrads; the tapetum then desquamates from the anther wall and enwraps microspores; subsequently, the surrounded microspores collapse completely at late microspore and early bicellular pollen stages. Inheritance analysis showed that the male sterility was controlled by a single recessive gene, ostd (t). This gene was mapped between the SSR markers RM7434 and RM275 on chromosome 6, and the physical distance from RM7434 to RM275 is about 389 kb.