Effects of planting pattern and the first irrigation date on growth and yield of saffron (Crocus sativus L.)

Studies on crop improvement of saffron (Crocus sativus L.) can play an important role in development of this native crop. In this context, an experiment was conducted at Agricultural Research Station, Ferdowsi University of Mashhad, Iran, as a factorial based on randomized complete block design with three replications, during 2005-2010 years. First studied factor was planting pattern of saffron (planting distances of 20×5, 20×10, 20×15 and 20×20 cm) and the second one was irrigation management (first irrigation performed at the beginning of September, the beginning of October and early November). During these experiments these criteria were studied: fresh flowers yield, stigma dry yield, fresh and dry forage yield, number of mother corm, number of replacement corm, replacement number of corm per mother corm, the total weight of corms without scales, the total weight of scales, weight ratio of corm scales-less to scales, the total weight of corms, the average weight of corms, average diameter of corms, average number of buds per corm, the total number of buds, the percentage of corm with abnormal root, leaf dry weight and leaf area. The results showed that, only the planting pattern was affected the studied indexes and the influence of irrigation time and interaction effects between planting pattern and irrigation was not significant. The results of mean comparison showed that the pattern 10*20 cm was comparatively advantage in respect to the studied characteristics. As in this treatment more fresh flower yield (170 kg.ha-1), dry stigma yield (12 kg.ha-1), average weight of corms (9.2 g) and average corm diameter (1.5 cm) was observed. The highest yield of fresh and dry forage (3916 and 1276 kg.ha-1, respectively) was obtained in the pattern 5x20 cm, and then was located 10×20 cm. Moreover, the highest frequency of corm was stand in weight of less than three grams and less than two centimeters in diameter

PA1b, an insecticidal protein extracted from pea seeds (Pisum sativum): 1H﷓2-D NMR study and molecular modelling

International audiencePA1b (pea albumin 1, subunit b) is a 37-amino acid cysteine-rich plant defense protein isolated from pea seeds (Pisum sativum). It induces short-term mortality in several pests, among which the cereal weevils Sitophilus sp. (Sitophilus oryzae, Sitophilus granarius, and Sitophilus zeamais) that are a major nuisance for stored cereals, all over the world. As such, PA1b is the first genuine protein phytotoxin specifically toxic to insects, which makes it a promising tool for seed weevil damage control. We have determined the 3-D solution structure of PA1b, using 2-D homonuclear proton NMR methods and molecular modeling. The primary sequence of the protein does not share similarities with other known toxins. It includes six cysteines forming three disulfide bridges. However, because of PA1b resistance to protease cleavage, conventional methods failed to establish the connectivity pattern. Our first attempts to assign the disulfide network from NOE data alone remained unsuccessful due to the tight packing of the cysteine residues within the core of the molecule. Yet, the use of ambiguous disulfide restraints within ARIA allowed us to establish that PA1b belongs to the inhibitor cystine-knot family. It exhibits the structural features that are characteristic of the knottin fold, namely, a triple-stranded antiparallel β-sheet with a long flexible loop connecting the first to the second strand and a series of turns. A comparison of the structural properties of PA1b with that of structurally related proteins adopting a knottin fold and exhibiting a diverse range of biological activities shows that the electrostatic and lipophilic potentials at the surface of PA1b are very close to those found for the spider toxin ACTX-Hi:OB4219, thereby suggesting activity on ion channels