Dianthus chinensis L.: The Structural Difference between Vascular Bundles in the Placenta and Ovary Wall Suggests Their Different Origin.

Dianthus chinensis is a perennial herbaceous plant with great ornamental, botanical, ecological, and medicinal value. The pistil of D. chinensis is composed of two fused carpels with free central placenta and two separate styles. The placenta is a columnar structure extending about two-thirds the length of the maturing fruit, which is typical of the Caryophyllaceous. Traditionally, free central placenta is thought to have evolved from axial placenta by septal disappearance, and axial placenta to have occurred through fusion of conduplicate carpels with marginal placenta. However, the traditional opinion is becoming more and more inconsistent with the new data gained in recent research of angiosperm systematics. To clarify the origin of D. chinensis pistil, the present anatomical study was carried out. The results show that the vascular system of placenta is independent to that of the ovary wall in D. chinensis. Moreover, in the central part of placenta there are one or two amphicribral bundles, and correspondingly numerous ones in the pistil which supply the ovules/seeds. It is obvious that the central amphicribral bundles in placenta are comparable to the counterparts in branches but not to those in leaves or their derivatives. Therefore, it is reasonable to deduce that the placenta of D. chinensis was not derived from conduplicate carpels through fusion of collateral vascular bundles, and actually a floral axis with ovules/seeds laterally adhering. On the contrary, the ovary wall was the lateral appendages of the floral axis. The result of the present study is completely in agreement with Unifying Theory, in which the placenta is taken as an ovule-bearing branch. Except for D. chinensis, the similar vascular organization has been observed in placenta of numerous isolated taxa. But till now, it is uncertain that whether this vascular organization pattern is popular in the whole angiosperms or not. More intensive and extensive investigations are needed.

Vascular anatomy of kiwi fruit and its implications for the origin of carpels.

Kiwi fruit is of great agricultural, botanical, and economic interest. The flower of kiwi fruit has axile placentation, which is typical for Actinidiaceae. Axile placentation is thought derived through fusion of conduplicate carpels with marginal placentation according to the traditional doctrine. Recent progress in angiosperm systematics has refuted this traditional doctrine and placed ANITA clade rather than Magnoliaceae as the basalmost clade. However, the former traditional doctrine stays in the classrooms as the only teachable theory for the origin of carpels. To test the validity of this doctrine, we performed anatomical study on kiwi fruit. Our study indicates that the placenta has a vascular system independent of that of the ovary wall, the ovules/seeds are attached to the placenta that is a continuation of floral axis enclosed by the lateral appendages that constitute the ovary wall, and there are some amphicribral bundles in the center of placenta and numerous amphicribral bundles supplying ovules/seeds in kiwi fruit. The amphicribral vascular bundles supplying the ovules/seeds are comparable to those usually seen in branches, but not comparable to those seen in leaves or their derivatives. This comparison indicates that the placenta in kiwi fruit cannot be derived from the fusion of collateral ventral bundles of conduplicate carpels, as suggested by traditional doctrine. Instead the vascular organization in placenta of kiwi suggests that the placenta is a shoot apex-bearing ovules/seeds laterally. This conclusion is in line with the recently raised Unifying Theory, in which the placenta is taken as an ovule-bearing branch independent of the ovary wall (carpel in strict sense). Similar vascular organization in placenta has been seen in numerous isolated taxa besides kiwi fruit. Therefore whether such a pattern is applicable for other angiosperms is an interesting question awaiting answering.

[Heat stress characteristics of photosystem II in eggplant].

With lower-and higher heat-resistant varieties of eggplant (Solanum melongena L.) Heibei I and Heibei II as test materials, and by using Plant Efficiency Analyzer (PEA) from Hansatech, this paper measured the fast chlorophyll a fluorescence transient and its parameters. The results showed that PS II construction became more sensitive to heat stress when ambient temperature was higher than 40 degrees C. The F0 went up slowly, and Fv/Fm and deltaF/Fm' came down dramatically. Heibei II had a longer semi-attenuation temperature of Fv/Fm (T50) and deltaF/Fm' (t50) than Heibei I. Under strong heat stress (5 min at 48 degrees C or 20-30 min at 44 degrees C), the K-step in relation to the inactivation of oxygen-evolving complex appeared in fluorescence rise at about 700 micros, and the regular O-J-I-P transient was transformed to O-K-J-I-P one. The K-phase of Heibei I and Heibei II appeared when the treatment time was up to 20 and 30 minutes at 44 degrees C, respectively. In comparing with 35 degrees C heat treatment, the DI0/RC in the parameters of Strasser's specific energy fluxes model was increased by a great extent under 48 degrees C or more heat stress, reflecting a strong safeguard of energy dissipation to PS II. When the temperature of heat stress increased from 35 degrees C to 52 degrees C, the Fvi/Fv of PS II silent reaction centers of Heibei I and Heibei II increased remarkably.

[Application of selective microelectrode in plant physiological research].

Selective microelectrode technique, known as an electrophysiological approach, can be used to measure directly specific information on ion or molecule distribution and movement both inside and outside of living organelle, biological cells, tissue and organs. It has several advantages over other methods in measuring ionic or molecular information, e.g. easy to handle, fast response, high sensitivity (10(-12) moles cm(-2) s(-1)) and non-invasive to the samples in addition to continuous measurement and automatic monitoring. Microscopic-scale selective electrode (with a tip diameter of 0.5-5 microm) can be used to measure net fluxes of ions or molecules outside of growing biological cells, tissues and organs, to measure activities of ions or molecules inside of growing organelle and biological cells. Thus, it has many applications in various research fields. The technical principle of design and use of selective microelectrode and its progress and development prospect in plant physiological research are summarized.