StHAB1, a negative regulatory factor in abscisic acid signaling, plays crucial roles in potato drought tolerance and shoot branching.

Abscisic acid (ABA) is critical in drought tolerance and plant growth. Group A protein type 2C phosphatases (PP2Cs) are negative regulators of ABA signaling and plant adaptation to stress. Knowledge about the functions of potato group A PP2Cs is limited. Here, we report that the potato group A PP2C StHAB1 is broadly expressed in potato plants and strongly induced by ABA and drought. Suppression of StHAB1 enhanced potato ABA sensitivity and drought tolerance, whereas overexpression of the dominant mutant StHAB1G276D compromised ABA sensitivity and drought tolerance. StHAB1 interacts with almost all ABA receptors and the Snf1-Related Kinase OST1. Suppressing StHAB1 and overexpressing StHAB1G276D alter potato growth morphology; notably, overexpression of StHAB1G276D causes excessive shoot branching. RNA-sequencing analyses identified that the auxin efflux carrier genes StPIN3, StPIN5, and StPIN8 were up-regulated in StHAB1G276D-overexpressing axillary buds. Correspondingly, the auxin concentration was reduced in StHAB1G276D-overexpressing axillary buds, consistent with the role of auxin in repressing lateral branch outgrowth. The expression of BRANCHED1s (StBRC1a and StBRC1b) was unchanged in StHAB1G276D-overexpressing axillary buds, suggesting that StHAB1G276D overexpression does not cause axillary bud outgrowth via regulation of BRC1 expression. Our findings demonstrate that StHAB1 is vital in potato drought tolerance and shoot branching.

Profiling and simultaneous quantitative determination of oligostilbenes in Paeonia ostii seed shell from different geographical areas in China and their comparative evaluation.

INTRODUCTION: The Paeonia ostii T. Hong & J. X. Zhang seed shell, characterised by a high content of oligostilbenes, is one of the two most important by-products in the preparation of seed oil. Oligostilbenes are considered characteristic constituents of the genus Paeonia, and can be used in fingerprinting to determine the geographical origin and the quality of raw materials. OBJECTIVE: To develop and optimise a simple and reproducible high-performance liquid chromatography diode array detection (HPLC-DAD) method for the simultaneous determination of seven oligostilbenes in P. ostii seed shell from different geographical areas, and to associate the cultivation area. METHODOLOGY: A validated HPLC method coupled with a DAD detector was performed for the detection and determination of target compounds in the samples. Optimal chromatographic conditions were achieved using an Agilent Zorbax Eclipse SB-AQ-C18 column and a gradient elution with acetonitrile and potassium dihydrogen phosphate solution. RESULTS: The proposed quantitative method showed appropriate accuracy and precision, and was successfully applied to the routine analysis of seven oligostilbenes and the quality evaluation of 50 P. ostii seed shell samples. There were significant differences between the contents of the seven oligostilbenes in different samples (P < 0.01). CONCLUSION: The results demonstrated that the oligostilbenes were main secondary metabolites in the P. ostii seed shells, and the content of seven components in P. ostii seed shells sourced from different cultivation areas in China was different.

Amylases StAmy23, StBAM1 and StBAM9 regulate cold-induced sweetening of potato tubers in distinct ways.

Cold-induced sweetening (CIS) in potato is detrimental to the quality of processed products. Conversion of starch to reducing sugars (RS) by amylases is considered one of the main pathways in CIS but is not well studied. The amylase genes StAmy23, StBAM1, and StBAM9 were studied for their functions in potato CIS. StAmy23 is localized in the cytoplasm, whereas StBAM1 and StBAM9 are targeted to the plastid stroma and starch granules, respectively. Genetic transformation of these amylases in potatoes by RNA interference showed that ß-amylase activity could be decreased in cold-stored tubers by silencing of StBAM1 and collective silencing of StBAM1 and StBAM9. However, StBAM9 silencing did not decrease ß-amylase activity. Silencing StBAM1 and StBAM9 caused starch accumulation and lower RS, which was more evident in simultaneously silenced lines, suggesting functional redundancy. Soluble starch content increased in RNAi-StBAM1 lines but decreased in RNAi-StBAM9 lines, suggesting that StBAM1 may regulate CIS by hydrolysing soluble starch and StBAM9 by directly acting on starch granules. Moreover, StBAM9 interacted with StBAM1 on the starch granules. StAmy23 silencing resulted in higher phytoglycogen and lower RS accumulation in cold-stored tubers, implying that StAmy23 regulates CIS by degrading cytosolic phytoglycogen. Our findings suggest that StAmy23, StBAM1, and StBAM9 function in potato CIS with varying levels of impact.